September 12, 1995. Copyright, 1995, Graphic News. All rights reserved

PAPWORTH HOSPITAL TO TRANSPLANT PIG HEARTS INTO HUMANS
By Nicholas Booth, Science Editor

LONDON, September 12, Graphic News- There have been monkeys, chimpanzees and baboons Ð now itÕs the turn of the humble pig, as doctors at Papworth Hospital announce today that they will perform their first animal-to-human heart transplants next year. At a press conference this morning, the Papworth team, led by Dr David White and Mr John Wallwork, revealed they have successfully transplanted pig hearts into specially-bred research monkeys. ÔThe results are way beyond what we expected,Õ Dr. White said.

The Papworth team are now confident that they can make the step from monkeys to humans. By use of genetic engineering, the Papworth doctors believe that they can beat the rejection which has thwarted the success of many animal-to-human organ transplants. The first attempt to transplant a pig heart into a monkey in the U.S. ended after just 30 hours. The British team have demonstrated that their monkeys can last for over 60 days with transplanted pig hearts.

The Papworth team chose pigs because their hearts are similar in size to human ones and they also breed very quickly. They injected human DNA into fertilized sowsÕ eggs and cross bred the three subsequent generations of litters. A thousand of them have been bred and from those, ten have had their hearts transplanted into monkeys. This research has been carried out by Imutran, a Cambridge-based genetic engineering company, set up by Dr. White in 1984. 

Because they carry human genes, the pig hearts are less likely to be rejected by the recipients. By mimicking the natural immunosuppression in humans, the doctors believe that human patients will survive for longer. Without the genetically-engineered immunosuppression, Imutran found that eight monkeys survived for an average of 5.1 days. With the genetically-engineered pig hearts, 10 monkeys lasted for more than 40 days and two survived for more than two months. ÔOur data shows clearly that we have found a way to trick the immune system of a primate into accepting a pig organ,Õ says Dr. White.

Papworth performed its first human heart transplant in 1979 and has to date carried out some 650 heart transplants, averaging roughly one a week. But this impressive record is insufficient to meet the demand of 6,000 patients who are currently in urgent need of heart transplants. More than half these patients will die because of an acute shortage of human donors. The use of genetically-engineered animal organs is seen as a major step forward in reducing this shortfall.  

The Papworth team believe it will only be a year before the first human being will become a recipient of a pigÕs heart. A clinical trial of around six patients will be carried out in 1996, but the doctors stressed that it will be several years before animal transplants will become routine in medicine. 

Sources: Imutran, Papworth Hospital.